1. Field
The present disclosure relates to a robot cleaner.
2. Background
A robot cleaner is an apparatus that automatically cleans a floor by suctioning foreign substances, such as dust, while traveling autonomously within a zone to be cleaned. The robot cleaner may sense distances to detected obstacles in the cleaning zone, such as furniture, office equipment, or walls, and the robot cleaner may, correspondingly, map the obstacles within the cleaning zone and maneuver to avoid the obstacles by controlling an application of a driving force to one or more wheels included in the robot cleaner.
The distance traveled by the robot cleaner from a given location has been measured using a sensor that observes movements of the robot cleaner relative to a nearby ceiling or floor. A location of a detected obstacle (i.e., the distance of the obstacle from a given location) has been calculated based on the measured distance traveled by the robot cleaner from the given location before encountering the obstacle. However, this measurement of the distance to the obstacle is an indirect estimate based on the travel distance of the robot cleaner, and inaccuracies in measuring the travel distance of the robot cleaner results in errors in determining the location of the obstacles. Errors in determining the travel distance may arise due to, for example, indentations in the floor. In another example, a robot cleaner may perform distance measurements by emitting infrared light or ultrasonic waves and measuring reflections from obstacles, and these types of measurement techniques may cause a considerable error due to the large amount of light or sound being scattered by obstacles.
Korean Patent Laid-Open Publication No. 10-2013-0141979 (hereinafter referred to as “'979 disclosure”) discloses a robot cleaner that includes a light source module configured to emit light in a cross-shaped pattern and a camera module configured to capture an image in front of the cleaner. The robot cleaner extracts the pattern from the image obtained via the camera module, and recognizes obstacles in the cleaning zone based on the extracted pattern. However, the range within which obstacles may be sensed by this robot cleaner is limited, and the robot cleaner cannot recognize a three-dimensional shape of an obstacle that vertically extends above a certain height.
For example, the robot cleaner in the '979 disclosure may not sense an obstacle that is located higher than the light source module or an obstacle that is higher from the floor than the light source module due to the nature of the cross-shaped pattern of light being emitted toward the floor in the cleaning zone. In the '979 disclosure, the height of an obstacle may be measured, to some extent, by using a vertical line pattern of light emitted from the camera module to radiate a portion of the obstacle. However, this technique enables the robot cleaner to collect information only about the portion of the obstacle that is irradiated with the vertical line pattern of light.
For example, when an obstacle such as a bed having a mattress placed on bed legs with a predetermined space is defined below the mattress, a control unit of the robot cleaner may fail to identify the mattress because the cross-shaped pattern of light emitted from the light source module is directed to the floor in the space and would not radiate the mattress. Since no obstacle would be detected, the control unit would control the robot cleaner to continue to travel toward the bed, where robot cleaner may collide with a structure, such as a frame that supports the mattress, and be prevented from entering the space, or may become jammed within this space between the floor and the frame.
The above reference is incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.